Sir, in chapter 11 of Ashby in the 11.1 introduction section the first line of the second paragraph talks of a third material in between the two materials during friction process. this point is not clear sir.

Take a look at Eqn. 11.6 on page 233. The load transmitted is proportional to area of contact and yield strength. In the case of soft materials, area of contact is high ( point contacts can easily flatten and form junctions of larger area); so, load transmitted and hence the dry friction coefficient is high.

sir,
we want to minimize the power loss but by using hybrid cables with core of copper, we are increasing the resistivity twice as coppper cable cable only..which inturn increases the power loss.. Is it minimises the power loss along providing the strength ?